Oh please. "Break down the foundations of our civilization?" Honestly, that's such hyperbole it is laughable. There is nothing wrong with letting two consenting adults get married. Nothing. I'm actually secure enough in my marriage to not be threatened in the slightest bit by gays getting married. If you are not that secure in your marriage, I'm sorry for you.
Now we get to the root of things, eh?
The Word of God, the founders of our country (you do know who passed the original laws against sodomy, don't you?), and all of western civilization until this depraved generation of liberals have called it wrong. The vast majority of modern Americans still know it is wrong.
The destructions wrought on the practitioners and those around them by this 'lifestyle' are well-documented and well-known.
I think I will follow my conscience and the wisdom of the ages, thank you very much, and ignore your lack of a moral compass and historical ignorance.